Point source emit- ters_ Line source emitters Classifica- tion

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Point source emit- ters_ Line source emitters Classifica- tion Powered By Docstoc
					 Point source emit-     B-6160
                        01-05




   ters, Line source
 emitters Classifica-
 emitters, Classifica-
Basics of
 tion of microirriga-
  Microirrigation
 ti        itt   Drip
 tion emitters, D i
  emitters, Pressure
  Point source                                                                     Point source
 emitters, Line                                                                   emitters, Line
  source emit-                                                                     source emit-
    ters, Clas-                                                                      ters, Clas-
   sification of                                                                     sification of
microirrigation                                                                  microirrigation
 emitters, Drip                                                                   emitters, Drip
emitters, Pres-                                                                  emitters, Pres-
sure compen-                                                                     sure compen-
 sated emitter,                                                                   sated emitter,
  Micro-sprin-                                                                     Micro-sprin-
  kler, bubbler,                                                                   kler, bubbler,
  Vortex, spa-
ghetti, Soaking
   hose, Single
                     Basics of                                                     Vortex, spa-
                                                                                 ghetti, Soaking
                                                                                    hose, Single
  walled, Emit-
ter inserted in
 line, Twin wall
   drip tubing,
  Wetting pat-
                      Microirrigation                                              walled, Emit-
                                                                                 ter inserted in
                                                                                  line, Twin wall
                                                                                    drip tubing,
                                                                                   Wetting pat-
   tern, Pig tail,                                Juan Enciso                       tern, Pig tail,
Emitter on the                                         And                       Emitter on the
  line, Double                                    Dana Porter                      line, Double
line with emit-                                                                  line with emit-
   ters, Micro-                  Assistant Professors and Extension Agricultural ters, Micro-
spinklers, Sand                              Engineering Specialists,            spinklers, Sand
     separator                    Texas A&M University, Weslaco and Lubbock           separator
  filter, Screen                                                                    filter, Screen
    filter, Sand                                                                      filter, Sand
media filter, In-                                                                 media filter, In-
 jection pump,                                                                    jection pump,
 Atmospheric                                                                       Atmospheric
      Vacuum                                                                           Vacuum
breaker, Check                                                                   breaker, Check
    valve Point                                                                      valve Point
  source emit-                                                                     source emit-
     ters, Line                                                                       ters, Line
  source emit-                                                                     source emit-
    ters, Clas-                                                                      ters, Clas-
   sification of                                                                     sification of
microirrigation                                                                  microirrigation
 emitters, Drip                                                                   emitters, Drip
emitters, Pres-                                                                  emitters, Pres-
sure compen-                                                                     sure compen-
 sated emitter,                                                                   sated emitter,
  Micro-sprin-                                                                     Micro-sprin-
  kler, bubbler,                                                                   kler, bubbler,
  Vortex, spa-                                                                     Vortex, spa-
ghetti, Soaking                                                                  ghetti, Soaking
   hose, Single                                                                     hose, Single
  Point source                                                                                                          Point source
 emitters, Line                                                                                                        emitters, Line
  source emit-                                                                                                          source emit-
    ters, Clas-                                                                                                           ters, Clas-
   sification of                                                                                                          sification of
microirrigation                                                                                                       microirrigation




                      m
 emitters, Drip                                                                                                        emitters, Drip
emitters, Pres-                                                                                                       emitters, Pres-
                                       icroirrigation involves frequent application of small
sure compen-                                                                                                          sure compen-
                                       quantities of water as drops (drip irrigation), tiny streams
 sated emitter,                                                                                                        sated emitter,
                                       (micro-sprinklers) or a miniature spray (micro-sprayers), using
  Micro-sprin-                                                                                                          Micro-sprin-
                   applicators placed along a water delivery line. The outlet device that applies
  kler, bubbler,                                                                                                        kler, bubbler,
                   water to the soil is called an emitter. Emitters dissipate the pressure of the pipe
  Vortex, spa-                                                                                                          Vortex, spa-
                   distribution network through a small orifice or by a long, narrow flow path,
ghetti, Soaking                                                                                                       ghetti, Soaking
                   applying water in small quantities at low pressure. Emitters partially wet the soil,
   hose, Single                                                                                                          hose, Single
                   moving water horizontally and vertically.
  walled, Emit-                                                                                                         walled, Emit-
ter inserted in                                                                                                       ter inserted in
 line, Twin wall                                                                                                       line, Twin wall
   drip tubing,                                                                                                          drip tubing,
  Wetting pat-                                                                                                          Wetting pat-
   tern, Pig tail,         Advantages and Disadvantages of Microirrigation                                               tern, Pig tail,
Emitter on the The main advantages of microirrigation are:                                                            Emitter on the
  line, Double         1. Uniformity. When properly designed and installed, microirrigation systems can obtain          line, Double
line with emit-           uniformities higher than 90 percent.                                                        line with emit-
   ters, Micro-        2. Fertilization control and chemigation. Because of their high uniformity,                       ters, Micro-
spinklers, Sand           microirrigation systems can apply fertilizers and chemicals along with water, frequently in spinklers, Sand
                          small quantities, increasing application efficiencies and minimizing chemical losses through
     separator                                                                                                            separator
                          deep percolation or drifting.
  filter, Screen        3. Labor savings. Microirrigation systems require less labor than do surface irrigation          filter, Screen
    filter, Sand           systems, although such systems do not necessarily reduce management requirements.               filter, Sand
media filter, In-       4. Water savings. By minimizing water loses through deep percolation and runoff,               media filter, In-
 jection pump,            microirrigation systems conserve water when irrigating crops with shallower root             jection pump,
                          systems such as vegetable crops or crops planted in sandy soils that hold little water.
 Atmospheric                                                                                                            Atmospheric
                          Also, some crops respond better to frequent, light water applications, resulting in higher
      Vacuum              yields and/or improved product quality.                                                           Vacuum
breaker, Check         5. Deficit irrigation. When water is limited and water available per unit area is low due       breaker, Check
    valve Point           to low capacities of canal systems or irrigation wells, microirrigation systems can spread valve Point
  source emit-            small amounts of water over a bigger area.                                                    source emit-
     ters, Line The main disadvantages of microirrigation are:                                                             ters, Line
  source emit-         1. High initial cost. These systems cost more to install than do surface and sprinkler           source emit-
    ters, Clas-           systems.                                                                                        ters, Clas-
   sification of        2. Maintenance and operation. Microirrigation systems require increased maintenance, sification of
                          with periodic injections of sulfuric acid and chlorine or other chemicals to avoid plugging
microirrigation           of emitters.
                                                                                                                      microirrigation
 emitters, Drip        3. Higher skills. Proper, safe use of injection chemicals needed for system maintenance         emitters, Drip
emitters, Pres-           and fertigation requires knowledge of chemical reactions between water and injected         emitters, Pres-
sure compen-              chemicals to avoid precipitation and plugging the tape. Microirrigation also requires       sure compen-
 sated emitter,           knowledge about calculating irrigation times and injection rates.                            sated emitter,
  Micro-sprin-                                                                                                          Micro-sprin-
  kler, bubbler,                                                                                                        kler, bubbler,
  Vortex, spa-                                                                                                          Vortex, spa-
ghetti, Soaking                                                                                                       ghetti, Soaking
   hose, Single                                                                                                          hose, Single5
  Point source                                                                                                             Point source
 emitters, Line                                                                                                           emitters, Line
  source emit-                                                                                                             source emit-
    ters, Clas-                                       Emitter Classification                                                  ters, Clas-
   sification of       Emitters are classified mainly as point source emitters or line source emitters, according to          sification of
microirrigation    their position in their supplying laterals.                                                           microirrigation
 emitters, Drip Point source emitters                                                                                    emitters, Drip
emitters, Pres- Point source emitters are best suited to irrigate trees, bushes and other similarly managed              emitters, Pres-
sure compen- plants. Single emitters can be inserted directly in a lateral or can be connected at the end of a           sure compen-
                   micro-tube (spaghetti). The main types of point-source emitters are single drip emitters, bubblers,
 sated emitter,                                                                                                           sated emitter,
                   micro sprinklers and spray emitters.
  Micro-sprin-                                                                                                             Micro-sprin-
                   Drip emitters
  kler, bubbler,      In drip irrigation (sometimes referred to as trickle irrigation), drip emitters each applying less
                                                                                                                           kler, bubbler,
  Vortex, spa- than 2 gallons per hour are inserted into plastic pipe or hose. Many possible configurations of              Vortex, spa-
ghetti, Soaking drip emitters are used to decrease pressure and distribute water from pipes to the soil. Those           ghetti, Soaking
   hose, Single configuration use small holes, long passageways, vortex chambers or discs. Pressure-compensated hose, Single
  walled, Emit- emitters deliver constant flow rates even when pressure supplied to the emitter varies.                     walled, Emit-
ter inserted in Bubblers                                                                                                 ter inserted in
 line, Twin wall The orifices on bubble emitters are larger than those on drip emitters and produce small                  line, Twin wall
                   water streams rather than sprays. Water is applied to the soil surface and moves down into root
   drip tubing, zones. Bubblers can control water delivery patterns to avoid spraying streets, fences, brick walls          drip tubing,
  Wetting pat- or windows. Such emitters are ideal for shrub plantings, trees, containers and flower beds and can Wetting pat-
   tern, Pig tail, apply up to 35 gallons per hour. Emitter plugging also occurs less often with bubbler emitters than tern, Pig tail,
Emitter on the with smaller-orifice drip emitters.                                                                        Emitter on the
  line, Double Micro-sprinklers                                                                                            line, Double
line with emit- Micro-sprinklers consist of an orifice with a deflector; water comes out of the micro-sprinkler line with emit-
   ters, Micro- orifice and crashes into the deflector to spray the soil. These sprinklers may or may not spin.               ters, Micro-
                   Wetting patterns depend on micro-sprinkler/deflector type. Some micro-sprinklers have fixed,
spinklers, Sand removable parts. Those with movable parts consist of deflectors that move as they are hit by              spinklers, Sand
     separator water exiting the orifice. Micro-sprinklers generally are connected to a micro-tube, often referred separator
  filter, Screen to as “spaghetti tubing.”                                                                                  filter, Screen
    filter, Sand       Micro-sprinklers are used in orchards, greenhouses and flower beds. They can apply from 3               filter, Sand
media filter, In-   to 138 gallons of water per hour; the higher the flow rate and pressure, the longer the wetted         media filter, In-
                   diameter. However, small flow rates are preferred in large orchards with large-diameter laterals.
 jection pump,                                                                                                            jection pump,
 Atmospheric Micro-sprayers                                                                                               Atmospheric
                      Micro-spray irrigation sprays water over mass plantings, ground cover, annual flower beds
      Vacuum and containers. It lowers soil temperature for rooting and plant propagation and even provides                    Vacuum
breaker, Check limited frost protection. The micro-sprayer produces tiny droplets and has a relatively small             breaker, Check
    valve Point wetting diameter. Its spray or mist is produced by a flat spreader and a small orifice operating at a valve Point
  source emit- pressures between 30 and 43 pounds per square inch (psi).                                                   source emit-
     ters, Line                                                                                                               ters, Line
  source emit-                                                                                                             source emit-
    ters, Clas- Outlet                                                                                                       ters, Clas-
   sification of                                                                                                             sification of
microirrigation                                                                                                          microirrigation
 emitters, Drip                                                                                                          emitters, Drip
emitters, Pres-                                                     Regular           Extra                              emitters, Pres-
sure compen-                                                        pressure        pressure                             sure compen-
 sated emitter,                Inlet                                         Pressure compensated emitter                 sated emitter,
  Micro-sprin-                                                                                                             Micro-sprin-
                    Drip emitters (long path spiral grooved)
  kler, bubbler,                                                                                                           kler, bubbler,
                   Fig. 1a. Classification of microirrigation emitters.
  Vortex, spa-                                                                                                             Vortex, spa-
ghetti, Soaking                                                                                                          ghetti, Soaking
6  hose, Single                                                                                                             hose, Single
  Point source                                                                                            Point source
 emitters, Line                                                                                          emitters, Line
  source emit-                                                                                            source emit-
    ters, Clas-                                                                                             ters, Clas-
   sification of                               61 cm                                                        sification of
microirrigation                                                                                         microirrigation
 emitters, Drip                               91 cm                                                      emitters, Drip
emitters, Pres-                                                                                         emitters, Pres-
                                             122 cm
sure compen-                                                                                            sure compen-
 sated emitter,                                                                                          sated emitter,
                                              152 cm
  Micro-sprin-                                                                                            Micro-sprin-
  kler, bubbler,                                                                                          kler, bubbler,
                                           Spaghetti
  Vortex, spa-                                                                                            Vortex, spa-
ghetti, Soaking                                                                                         ghetti, Soaking
   hose, Single                                                         Micro-sprinkler                    hose, Single
  walled, Emit-                                                                                           walled, Emit-
ter inserted in                                                                                         ter inserted in
 line, Twin wall                                                                                         line, Twin wall
   drip tubing,                                                                                            drip tubing,
  Wetting pat-                 Soaking hose                                                               Wetting pat-
   tern, Pig tail,                                                                                         tern, Pig tail,
Emitter on the                                                                                          Emitter on the
  line, Double                                                                                            line, Double
line with emit-                                                                      Vortex             line with emit-
   ters, Micro-                                                                               Bubbler      ters, Micro-
spinklers, Sand                                                                                         spinklers, Sand
     separator                                                                                               separator
  filter, Screen              Single walled                                                                filter, Screen
    filter, Sand                                                                                             filter, Sand
media filter, In-                                                                                        media filter, In-
 jection pump,                                                                                           jection pump,
 Atmospheric                                                                                              Atmospheric
      Vacuum                                                                                                  Vacuum
breaker, Check                                                                                          breaker, Check
    valve Point                                                                                             valve Point
  source emit-                                             Emitter inserted in line                       source emit-
     ters, Line                                                                                              ters, Line
  source emit-                                                  Exit orifice                              source emit-
    ters, Clas-                                             Inner orifice
                                                                                                            ters, Clas-
   sification of                                                                                            sification of
microirrigation                                                                                         microirrigation
 emitters, Drip                                                                                          emitters, Drip
                                                                             Main chamber
emitters, Pres-                                                                                         emitters, Pres-
sure compen-                                                Twin wall drip tubing                       sure compen-
 sated emitter,                                                                                          sated emitter,
  Micro-sprin-                                                                                            Micro-sprin-
  kler, bubbler,                                                                                          kler, bubbler,
  Vortex, spa- Fig. 1b. Classification of microirrigation emitters.                                       Vortex, spa-
ghetti, Soaking                                                                                         ghetti, Soaking
   hose, Single                                                                                            hose, Single7
  Point source                                                                                                             Point source
 emitters, Line                                                                                                           emitters, Line
  source emit-                                                                                                             source emit-
    ters, Clas-
                   Line source emitters                                                                                      ters, Clas-
                      Line source emitters consist of drip tubing with supply orifices to meter water before it enters
   sification of the line; then, the water passes through a labyrinth of flow paths to dissipate or compensate                sification of
microirrigation pressure and exits to one or more distribution orifices. Line source emitters use three main              microirrigation
 emitters, Drip tubing configurations:                                                                                     emitters, Drip
emitters, Pres- Soaker hose                                                                                              emitters, Pres-
sure compen- Soaker hoses use porous tubing to leak water continuously along the tube length rather than sure compen-
 sated emitter, through discreet emitters.                                                                                sated emitter,
  Micro-sprin-     Single walled tubing                                                                                    Micro-sprin-
  kler, bubbler,      This kind of tubing, generally less than one inch in diameter, has built-in, inserted or attached    kler, bubbler,
                   emitters.
  Vortex, spa-                                                                                                             Vortex, spa-
ghetti, Soaking Double walled or twin wall tubing                                                                        ghetti, Soaking
                      These drip lines have two walls forming parallel flow paths; one path delivers water along the
   hose, Single length of the tubing, and one contains outlets to deliver water to the soil at set intervals (Fig. 1). hose, Single
  walled, Emit-                                                                                                            walled, Emit-
ter inserted in                                      Soil Wetting Patterns                                               ter inserted in
 line, Twin wall Drip irrigation wets just part of plants’ total root-zone area. The percentage of an area wetted line, Twin wall
   drip tubing, is determined by soil properties, spacing of emitters, spacing of tape laterals and managing                drip tubing,
  Wetting pat- irrigation rates and timing. The minimum recommended wetted area is 33 percent for agricultural Wetting pat-
   tern, Pig tail, row crops and 75 percent for landscaping. Thorough partial root-zone wetting with drip irrigation tern, Pig tail,
Emitter on the favors aeration of roots, which may increase crop productivity and/or improve health of landscape Emitter on the
                   plants.
  line, Double        Water applied to the soil produces a wetting pattern as it moves downward due to gravity             line, Double
line with emit- and horizontally due to differential soil moisture and capillary suction (Fig. 2). Wetting-pattern       line with emit-
   ters, Micro- configurations depend on soil type and tillage practices. For example, clay soils have fine particles ters, Micro-
spinklers, Sand that exert capillary forces greater than gravity, resulting in horizontal wetting patterns. Sandy soils, spinklers, Sand
     separator on the other hand, have coarser particles that produce faster downward movement of water.                     separator
                   Their bigger particles produce bigger voids, making it difficult for water to move horizontally.
  filter, Screen Most soils comprise a combination of clay, loam and sand particles. The shape of the wetting front filter, Screen
    filter, Sand is more proportional in medium-textured soils than in other soil types (Fig. 2). Wetting-pattern             filter, Sand
media filter, In- size will be affected by irrigation dripper-flow rate and application time. Increased application        media filter, In-
 jection pump,     time gives more opportunity for horizontal movement of water, especially in clay soils. Take into      jection pump,
 Atmospheric account soil characteristics when determining application times, numbers of emitters per plant                Atmospheric
                   and emitter flow rates.
      Vacuum                                                                                                                   Vacuum
breaker, Check                               Emitter                                                                     breaker, Check
    valve Point                                                                                                             valve Point
  source emit-                                                                                                             source emit-
     ters, Line                                                                                                               ters, Line
  source emit-                                                                                                             source emit-
    ters, Clas-                                                                                                              ters, Clas-
   sification of                                                                                                             sification of
microirrigation                                                                                                          microirrigation
                              Clay
 emitters, Drip                                                                                                           emitters, Drip
emitters, Pres-                                                                                                          emitters, Pres-
sure compen-                                                                                                             sure compen-
                                                                       Loam
 sated emitter,                                                                                                           sated emitter,
  Micro-sprin-                                                                                              Sand           Micro-sprin-
  kler, bubbler, Fig. 2. Wetting pattern shapes for the clay, loam and sand soil textures.                                 kler, bubbler,
  Vortex, spa-                                                                                                             Vortex, spa-
ghetti, Soaking                                                                                                          ghetti, Soaking
8  hose, Single                                                                                                             hose, Single
  Point source                                                                                                               Point source
 emitters, Line                                                                                                             emitters, Line
  source emit-                                                                                                               source emit-
    ters, Clas-                       Emitter Placement in Relation to Plants                                                  ters, Clas-
   sification of       Emitter placement and configuration affects water efficiency, plant germination and                       sification of
microirrigation    establishment, nutrient utilization efficiency and soil salinity. Emitter type and placement also affect microirrigation
                   wetted zone size and horizontal and downward movement of water. When you want a larger
 emitters, Drip wetted area, place more point source emitters per plant (Fig. 3). More emitters can be installed emitters, Drip
emitters, Pres- (1) by supplying them from the lateral using several spaghetti tubes or (2) by using a “pigtail            emitters, Pres-
sure compen- configuration” to feed several emitters from a line stemming from a lateral surrounding the plants. sure compen-
 sated emitter, Another option is to install two laterals instead of one, distributing several emitters along each. sated emitter,
  Micro-sprin-                                                                                                               Micro-sprin-
  kler, bubbler,                                                                                                             kler, bubbler,
  Vortex, spa-                                                                                                               Vortex, spa-
ghetti, Soaking                                                                                                            ghetti, Soaking
   hose, Single                                                                                                               hose, Single
  walled, Emit-                                                                                                              walled, Emit-
ter inserted in                                                                                                            ter inserted in
 line, Twin wall             Pig tail                        Emitter on the line                Double line with emitters line, Twin wall
   drip tubing,                                                                                                               drip tubing,
  Wetting pat-                                                                                                               Wetting pat-
   tern, Pig tail,                                                                                                           tern, Pig tail,
Emitter on the                                                                                                             Emitter on the
  line, Double                                                                                                               line, Double
line with emit-                                                                                                            line with emit-
   ters, Micro-                                                                                                               ters, Micro-
spinklers, Sand              Micro-sprinklers                                                                              spinklers, Sand
                                                                               Emitter connected with
     separator                                                                 micro-tubes or spaghettis                       separator
  filter, Screen                                                                                                              filter, Screen
    filter, Sand                                                                                                                filter, Sand
media filter, In-                                                                                                           media filter, In-
 jection pump,                                                                                                              jection pump,
 Atmospheric                    Line source emitters                                                                         Atmospheric
      Vacuum                    (tapes and drip tubing)                                                                          Vacuum
breaker, Check                                                                                                             breaker, Check
    valve Point                                                                                                               valve Point
  source emit-                                                                                                               source emit-
     ters, Line                                                                                                                 ters, Line
  source emit-                                                                                                               source emit-
    ters, Clas-                                                                                                                ters, Clas-
   sification of    Fig. 3. Installation configurations of point source and line source emitters.                              sification of
microirrigation                                                                                                            microirrigation
 emitters, Drip                                                                                                             emitters, Drip
emitters, Pres- Microsprinklers and bubblers generally are installed one per plant; wetted diameter than can emitters, Pres-
sure compen- be controlled with pressure and orifice size. For row crops, one lateral can be placed under each sure compen-
 sated emitter, row or can be used to irrigate two plant rows (Fig. 4). Configuration depends on factors such as sated emitter,
                   economics, crop tolerance to salinity and soil texture. Spacing between emitters along a lateral
  Micro-sprin- depends on the crop. For example, with onions, spacing should be close (less than 8 inches), but Micro-sprin-
  kler, bubbler, with cotton, it can be every 12 inches or more.                                                             kler, bubbler,
  Vortex, spa-                                                                                                               Vortex, spa-
ghetti, Soaking                                                                                                            ghetti, Soaking
   hose, Single                                                                                                                          9
                                                                                                                              hose, Single
  Point source                                                                                                               Point source
 emitters, Line                                                                                                             emitters, Line
  source emit-                                                                                                               source emit-
    ters, Clas-                                                                                                                ters, Clas-
   sification of                                                                                                               sification of
microirrigation                                                                                                            microirrigation
 emitters, Drip                                                                                                             emitters, Drip
emitters, Pres-                                                                                                            emitters, Pres-
sure compen- Fig. 4. Typical lateral placement a) under every row; under alternate furrows. This illustration shows sure compen-
 sated emitter, tape placement options for a row crop using 40 inch tow spacing.                                            sated emitter,
  Micro-sprin-                                                                                                               Micro-sprin-
                      Wetting patterns can be determined experimentally or by field trials, which can reveal effects
  kler, bubbler,                                                                                                             kler, bubbler,
                   of soil layers, compaction and soil variability. Different drip tapes can be tested with water flowing
  Vortex, spa- out of an elevated 50 gallon drum. Such trials allow better designs, and it can be especially helpful Vortex, spa-
ghetti, Soaking to consult irrigation professionals and producers experienced with microirrigation in a given area ghetti, Soaking
   hose, Single or for a particular crop.                                                                                     hose, Single
  walled, Emit-                                                                                                              walled, Emit-
ter inserted in                        Components of Microirrigation Systems                                               ter inserted in
 line, Twin wall Besides emitters, most microirrigation systems include a filter, chemigation units, a mainline,             line, Twin wall
   drip tubing, laterals and accessories such as pressure regulators, connections and vacuum and pressure relief drip tubing,
                   valves.
  Wetting pat-                                                                                                               Wetting pat-
   tern, Pig tail, Filters                                                                                                    tern, Pig tail,
Emitter on the          • Filters remove impurities that can cause clogging; they are located after the system             Emitter on the
                              pump, with multiple filters placed in parallel (side by side, discharging filtered water into
  line, Double                                                                                                               line, Double
                              the same line). The number of filters needed depends on flow rate and water quality,
line with emit-               including suspended particle size:                                                           line with emit-
   ters, Micro-                                                                                                               ters, Micro-
spinklers, Sand                                                                                                            spinklers, Sand
     separator                                      Particle Size Classification                                                 separator
  filter, Screen                                                                                                              filter, Screen
                            Material              Size (microns)                Size (in)            Mesh equivalent
    filter, Sand                                                                                                                filter, Sand
media filter, In- Very coarse sand                     1000-2000                  0.04-0.08                  15-7.5         media filter, In-
 jection pump,                                                                                                              jection pump,
                             Coarse sand               500-1000                  0.02-0.04                   30-15
 Atmospheric                                                                                                                 Atmospheric
      Vacuum                Medium sand                 250-500                  0.01-0.02                   60-30               Vacuum
breaker, Check                                                                                                             breaker, Check
                                 Fine sand              100-250                 0.004-0.01                  150-60
    valve Point                                                                                                                valve Point
  source emit-             Very fine sand                 50-100                0.002-0.004                 300-150           source emit-
     ters, Line                          Silt             2-50                0.00008-0.002               7500-300              ters, Line
  source emit-                                                                                                               source emit-
    ters, Clas-                         Clay               <2                     0.00008                    7500              ters, Clas-
   sification of                                                                                                               sification of
microirrigation       Filter screen openings should be one-fourth the size of emitter openings. Filtration capacity        microirrigation
 emitters, Drip is expressed in “mesh” (mesh numbers correspond to openings per inch, e.g., 200 mesh has 200 emitters, Drip
                   openings per inch). Most microirrigation applications require mesh sizes between 100 and 200.
emitters, Pres- The main types of filters are:                                                                              emitters, Pres-
sure compen-            • Sand Separator (centrifugal or hydrocyclone) filters are ideal for removing                       sure compen-
 sated emitter,               suspended sand particles (often encountered in pumping from deep wells). Centrifugal          sated emitter,
  Micro-sprin-                separators will remove particles down to 75 microns (200 mesh). These filters spin the          Micro-sprin-
  kler, bubbler,              water, using centrifugal force to remove high density particles (Fig. 5). Pressures for water kler, bubbler,
  Vortex, spa-                passing through the filters decrease by about 8 to 12 psi.                                      Vortex, spa-
ghetti, Soaking                                                                                                            ghetti, Soaking
10 hose, Single                                                                                                               hose, Single
  Point source                                                                                                                Point source
 emitters, Line                                                                                                              emitters, Line
  source emit-                                                                                                                source emit-
    ters, Clas-                                                      Outlet
                                                                                                                                ters, Clas-
   sification of                                                                                                                sification of
microirrigation                                                                                                             microirrigation
 emitters, Drip                                                                                                              emitters, Drip
emitters, Pres-          Inlet                                                                                              emitters, Pres-
sure compen-                                                                                                                sure compen-
 sated emitter,                                                                                                              sated emitter,
  Micro-sprin-                                                                                                                Micro-sprin-
  kler, bubbler,                                                                                                              kler, bubbler,
  Vortex, spa-                                                                                                                Vortex, spa-
ghetti, Soaking                                                                                                             ghetti, Soaking
                                                           Flush
   hose, Single Cleaning                                                                                                       hose, Single
  walled, Emit-         lid                                                                                                   walled, Emit-
ter inserted in                                                                                                             ter inserted in
 line, Twin wall Fig. 5. Sand separator (centrifugal) filter.                                                                line, Twin wall
   drip tubing,          • Screen-mesh filters (Fig. 6) come in different shapes and sizes, ranging from 20 to 200 drip tubing,
  Wetting pat-                mesh. Their mesh can be made of stainless steel, polyester or plastic and can remove            Wetting pat-
   tern, Pig tail,            very fine sand particles or very small algae. They serve as backup filters to catch particles tern, Pig tail,
Emitter on the                that get through other filters.                                                                Emitter on the
  line, Double                  Filtration process                                           Flushing
                                                                                                                              line, Double
line with emit-                                                Inlet                                                  Inlet line with emit-
   ters, Micro-                                                                                                                ters, Micro-
spinklers, Sand                                                                                                             spinklers, Sand
     separator                                                     Flush                                                        separator
  filter, Screen                                                                                                               filter, Screen
    filter, Sand            Outlet                                                                                               filter, Sand
media filter, In-                                                                                                            media filter, In-
                   Fig. 6. Screen filter.
 jection pump,                                                                                                               jection pump,
 Atmospheric             • Sand media filters contain a vertical cylinder with graded sand inside (Fig. 7). This               Atmospheric
      Vacuum                  cylinder efficiently separates organic material (algae, leaves, etc.) and fine sediment, so it        Vacuum
breaker, Check                often is used to filter water from surface sources such as lakes, rivers or canals. Multiple breaker, Check
    valve Point               cylinders can be back-flushed either manually or automatically.                                   valve Point
  source emit-                 Cleaning       Drain                                                                           source emit-
     ters, Line                    lid                                                                                           ters, Line
  source emit-                                                                                                                source emit-
    ters, Clas-           Inlet                                                                                                 ters, Clas-
   sification of                                                                                                                sification of
microirrigation                                                                                                             microirrigation
 emitters, Drip                                                                                                              emitters, Drip
emitters, Pres-                                                                                                             emitters, Pres-
sure compen-                                                    Outlet                                                      sure compen-
 sated emitter,                                                                                                              sated emitter,
  Micro-sprin-                                                                                                                Micro-sprin-
  kler, bubbler,                                                                                                              kler, bubbler,
  Vortex, spa-     Fig. 7. Sand media filter.                                                                                 Vortex, spa-
ghetti, Soaking                                                                                                             ghetti, Soaking
   hose, Single                                                                                                                       11
                                                                                                                               hose, Single
  Point source                                                                                                              Point source
 emitters, Line                                                                                                            emitters, Line
  source emit- Depending upon water source and quality, more than one type of filter may be needed for a                     source emit-
    ters, Clas- given irrigation system, with typical combinations as follows:                                                ters, Clas-
   sification of         1. If the water source is a deep well, a filter station may consist of a sand separator               sification of
microirrigation              followed by a screen, disk or media filter.                                                   microirrigation
 emitters, Drip         2. If the water source is a canal, a filter station may consist of a sand media filter combined emitters, Drip
                             with a screen filter or a disk filter with screen filter (Fig. 8).
emitters, Pres-                                                                                                           emitters, Pres-
sure compen- Chemigation Unit                                                                                             sure compen-
 sated emitter,        Microirrigation’s high distribution uniformity gives it great potential for uniformly and           sated emitter,
                   efficiently applying agricultural chemicals, a process called chemigation. The main components of a
  Micro-sprin-                                                                                                              Micro-sprin-
                   chemigation unit are a chemical solution tank, an injection system and chemigation safety devices.
  kler, bubbler, [YOU LIST THE CHEMICAL SOLUTION TANK BUT DO NOT DISCUSS IT.]                                               kler, bubbler,
  Vortex, spa- Chemical Solution Tanks                                                                                      Vortex, spa-
ghetti, Soaking Chemical solution tanks generally are constructed of poly or fiberglass. A conical form at the ghetti, Soaking
   hose, Single tank bottom facilitates flushing it completely so that no material is wasted. Tanks should have an            hose, Single
  walled, Emit-    easy-clean screen downstream of the valve to make them easier to clean.                                  walled, Emit-
ter inserted in Injection system                                                                                          ter inserted in
 line, Twin wall The main types of chemical injectors are the venturi injector, injection pump, and the                    line, Twin wall
   drip tubing, differential tank (Fig. 9). Criteria for selecting the proper injection system include cost, ease of         drip tubing,
                   use/repair, durability and susceptibility to corrosion.
  Wetting pat- With venturi injectors, water is extracted from the main line, then (1) pressure is added with a Wetting pat-
   tern, Pig tail, centrifugal pump (Fig. 9) or (2) a pressure differential is created by a valve in the mainline forcing tern, Pig tail,
Emitter on the water through the injector at high velocity. The high-velocity water passing through the throat            Emitter on the
  line, Double     of the venturi creates a vacuum or negative pressure, generating suction to draw chemicals into          line, Double
line with emit- the injector from the chemical tank. Although the venturi is cheaper than a positive displacement line with emit-
                   pump, its injection rate is more difficult to control.
   ters, Micro-        With injection pumps, water is pumped into the system using pistons, diaphragms or gears. An
                                                                                                                             ters, Micro-
spinklers, Sand injection pump has a small motor powered either by electricity or by energy from the water itself. spinklers, Sand
     separator The motor moves small pumps (diaphragms) or pistons to inject fertilizer into the system. The                  separator
  filter, Screen    advantage of injection pumps is that chemicals can be injected with high uniformity at rates easily filter, Screen
    filter, Sand adjusted regardless of discharge pressure.                                                                    filter, Sand
                       With differential tanks, water is forced through a tank containing the chemical to be injected. As
media filter, In- water passes into the tank, fertilizer is injected into the irrigation system.                           media filter, In-
 jection pump, One disadvantage of such a system is that the concentration of the chemical in the tank                     jection pump,
 Atmospheric decreases over time.                                                                                          Atmospheric
      Vacuum Chemigation safety devices                                                                                        Vacuum
breaker, Check Backflow can occur in a system due to cross connection between a water source and an                        breaker, Check
    valve Point irrigation system. For example, water may be turned off, but the chemical injection unit may                 valve Point
  source emit-     continue to work, contaminating the water source. To protect groundwater and drinking water              source emit-
                   supplies from chemical contamination, backflow – whether from backsiphonage or backpressure
     ters, Line – must be prevented. The main chemigation safety devices used to prevent backflow are shown in ters, Line
  source emit- Figure 10.                                                                                                   source emit-
    ters, Clas-        Backsiphonage is the reversal of normal system flow, caused by negative pressure (vacuum or             ters, Clas-
   sification of    partial vacuum) in the supplying pipe. Backsiphonage occurs due to low pressure in the water              sification of
microirrigation    source. For example, the mainline source pipe may break at a spot lower than the irrigation            microirrigation
                   system or pressure may be reduced drastically because a supply pump fails. Such situations can be
 emitters, Drip avoided by installing check values, vacuum relief valves or vacuum breaker valves.                        emitters, Drip
emitters, Pres- Backpressure is the reversal of normal system flow due to downstream pressure increasing                   emitters, Pres-
sure compen- above supply pressure. Backpressure may occur if a system operates at higher pressures than                  sure compen-
 sated emitter,    its water supply, perhaps due to use of booster pumps or interconnection of a water source to           sated emitter,
  Micro-sprin-     other water systems. Such situations can be avoided by installing double check valves or special         Micro-sprin-
                   valves that combine check values with reduced pressure zones inside them (commonly known as
  kler, bubbler, reduced pressure principle backflow prevention valves).                                                     kler, bubbler,
  Vortex, spa-                                                                                                              Vortex, spa-
ghetti, Soaking                                                                                                           ghetti, Soaking
12 hose, Single                                                                                                              hose, Single
  Point source                                                                                                   Point source
 emitters, Line                                                                                  Supply Tank    emitters, Line
  source emit-                                                                                                   source emit-
    ters, Clas-                                                                                                    ters, Clas-
   sification of                         If applicable, injection pump                                             sification of
microirrigation                         wire should be interlocked                                             microirrigation
                                        with irrigation system pump.
 emitters, Drip                                                                                                 emitters, Drip
emitters, Pres-                                                                                                emitters, Pres-
sure compen-                                                                                                   sure compen-
 sated emitter,                                                                                                 sated emitter,
                                                   Injection Pump
  Micro-sprin-                                                          Check    Screen                          Micro-sprin-
  kler, bubbler,                                                        valve                                    kler, bubbler,
  Vortex, spa-                                                                                                   Vortex, spa-
ghetti, Soaking                   Main Shut                                                                    ghetti, Soaking
   hose, Single                   Off Valve                                               Supply Tank             hose, Single
                                                        Supply Tank
  walled, Emit-                                                                                                  walled, Emit-
ter inserted in                                                                                                ter inserted in
 line, Twin wall                                                                                                line, Twin wall
   drip tubing,                                                                                                   drip tubing,
  Wetting pat-                                                                                                   Wetting pat-
   tern, Pig tail,                                                                                                tern, Pig tail,
Emitter on the                                                                                                 Emitter on the
  line, Double                                                                                                   line, Double
line with emit-                                                                                                line with emit-
   ters, Micro-                                                                                                   ters, Micro-
spinklers, Sand                                                                          Supply Tank           spinklers, Sand
     separator                                                                                                      separator
  filter, Screen                                                                                                  filter, Screen
    filter, Sand                                                                                                    filter, Sand
                                                          Supply Tank
media filter, In-                                                                                               media filter, In-
 jection pump,                                                                                                  jection pump,
 Atmospheric Fig. 9. Fertilizer injectors.                                                                       Atmospheric
      Vacuum                                                                                                         Vacuum
                                                     Float
breaker, Check                                                                                                 breaker, Check
    valve Point                                                                                                    valve Point
  source emit-                                                                                                   source emit-
     ters, Line                                                                                                     ters, Line
  source emit-                                                                                                   source emit-
    ters, Clas-                                                                                                    ters, Clas-
   sification of                                                            Check valve                            sification of
microirrigation                                                                                                microirrigation
 emitters, Drip                   Atmospheric Vacuum breaker                                                    emitters, Drip
emitters, Pres-                                                                                                emitters, Pres-
sure compen-                                                                                                   sure compen-
 sated emitter,              Double Check Valve Assembly                                                        sated emitter,
                                        Shut-off valves
  Micro-sprin-                                                                                                   Micro-sprin-
                                         Check valves
  kler, bubbler,                                                                                                 kler, bubbler,
  Vortex, spa-                                                                                                   Vortex, spa-
ghetti, Soaking                                                                                                ghetti, Soaking
   hose, Single
                 Fig. 10. Chemigation safety devices.
                                                                                                                          13
                                                                                                                  hose, Single
  Point source                                                                                                            Point source
 emitters, Line                                                                                                          emitters, Line
  source emit-                                                                                                            source emit-
    ters, Clas-
                   Laterals                                                                                                 ters, Clas-
                      Laterals are the flexible polyethylene tubing used to carry water to areas to be irrigated.
   sification of They deliver water to plants through spaced orifices or emitters. Layout of laterals is designed            sification of
microirrigation according to the dimensions and the topography of the fields to be irrigated. The diameter of a          microirrigation
 emitters, Drip lateral is determined according to hydraulic principles of pipe flow.                                     emitters, Drip
emitters, Pres- Vacuum and Pressure Relief Valves                                                                       emitters, Pres-
sure compen- Air sometimes enters irrigation pipes, accumulating and becoming trapped in the pipelines’                 sure compen-
 sated emitter, highest points. This trapped air can reduce water flow and increase compression, eventually               sated emitter,
  Micro-sprin- destroying pipes.Valves help to release the air during pipe filling and draining. An air valve consists     Micro-sprin-
  kler, bubbler, of a small orifice with a ball inside. When air is released, the ball lets the air escape but retains     kler, bubbler,
  Vortex, spa- the water. Pressure relief valves have an inside spring; when pressure inside the pipe exceeds             Vortex, spa-
                   the pressure of this spring, the valve opens, protecting the pipe from blowing. Pressure pipes are
ghetti, Soaking selected according to their resistance.                                                                 ghetti, Soaking
   hose, Single                                                                                                            hose, Single
  walled, Emit- Pressure regulators                                                                                       walled, Emit-
                      For areas with irregular topography, particularly in irrigation systems without pressure-
ter inserted in compensating emitters, pressure regulators must be used to produce uniform application of               ter inserted in
 line, Twin wall water. Pressure regulators dissipate excess pressure or reduce it to normal operating pressure of       line, Twin wall
   drip tubing, the emitters. Such regulators use one or more springs to decrease flow diameter and so reduce               drip tubing,
  Wetting pat- pressure. Generally, one pressure regulator is used to control pressure in two lines (Fig. 10).            Wetting pat-
   tern, Pig tail,                                                                                                         tern, Pig tail,
Emitter on the                                                Summary                                                   Emitter on the
  line, Double        Microirrigation systems can help create beautiful landscapes and improve yields and quality of      line, Double
                   agricultural crops, orchards and vineyards. This publication should have increased your knowledge
line with emit-                                                                                                         line with emit-
                   and understanding about microirrigation systems’ advantages and disadvantages and about their
   ters, Micro- components and configuration, as well as about the importance of placing them correctly in                  ters, Micro-
spinklers, Sand relation to soil and plant types for increased irrigation efficiency.                                    spinklers, Sand
     separator                                                                                                               separator
  filter, Screen                                                                                                           filter, Screen
    filter, Sand                                                                                                             filter, Sand
media filter, In-                                                                                                        media filter, In-
 jection pump,                                                                                                           jection pump,
 Atmospheric                                                                                                              Atmospheric
      Vacuum                                                                                                                  Vacuum
breaker, Check                                                                                                          breaker, Check
    valve Point                                                                                                             valve Point
  source emit-                                                                                                            source emit-
     ters, Line                                                                                                              ters, Line
  source emit-                                                                                                            source emit-
    ters, Clas-                                                                                                             ters, Clas-
   sification of                                                                                                            sification of
microirrigation                                                                                                         microirrigation
 emitters, Drip                                                                                                          emitters, Drip
emitters, Pres-                                                                                                         emitters, Pres-
sure compen-                                                                                                            sure compen-
 sated emitter,                                                                                                          sated emitter,
  Micro-sprin-                                                                                                            Micro-sprin-
  kler, bubbler,                                                                                                          kler, bubbler,
  Vortex, spa-                                                                                                            Vortex, spa-
ghetti, Soaking                                                                                                         ghetti, Soaking
14 hose, Single                                                                                                            hose, Single
                   Point source emit-
                    ters, Line source
                      i      Cl ifi




              bubbler, Vortex, spa-
              ghetti, Soaking hose,
            The information given herein is for educational purposes only. Reference to commercial products or trade names is made
            with the understanding that no discrimination is intended and no endorsement by Texas Cooperative Extension is implied.




              Single walled, Emit-
                              Produced by Agricultural Communications, The Texas A&M University System
                               Extension publications can be found on the Web at: http://tcebookstore.org

                                    Visit Texas Cooperative Extension at http://texasextension.tamu.edu




               ter inserted in line,
Educational programs conducted by Texas Cooperative Extension serve people of all ages regardless of socioeconomic level, race, color,
sex, religion, handicap or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended,
and June 30, 1914, in cooperation with the United States Department of Agriculture. Edward G. Smith, Interim Director, Texas Cooperative
Extension, The Texas A&M University System.
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